JPS586050A - Operating and spare power source switching control circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply circuit, and more particularly to a control circuit for switching between active and standby power supplies to improve the reliability of a power supply device.

Conventionally, this type of switching circuit for active and standby power sources has been constructed as shown in FIG. In other words, in the ta1 diagram,
PUI is a working DC stabilized power supply circuit, PU2 is a standby DC stabilized power supply circuit, 1 and 11 are unregulated DC power supplies,
2 and 12 are main control circuits, 3 and 13 are error amplifier circuits,
4 and 14 are reference voltage generation circuits, 9 is a load, Dl and D
ll is a reverse current blocking diode. In this circuit, in order to increase the accuracy of output voltage detection, voltage is detected between the terminals of the load 9, and the active unit PUI is the standby unit PUI.
It is set to obtain an output voltage slightly higher than that of U2, so the diode D1 is normally in a forward conduction state, and constant voltage controlled DC is supplied from the active unit PU1 to the load 9IC.

In this state, the detection voltage given to the error amplification circuit 13 of the standby unit PU2 is VL, which is slightly higher than the reference voltage Vr2 given to the error amplification circuit 13, so the main The control circuit 12 always operates to lower the output voltage Vc2, and in a steady state, the value of the output voltage Vc2 is zero.

If the active unit PUI stops due to a failure in this state, the standby unit PU2 must rise from an output voltage of zero volts and supply DC to the load 9 instead of the active unit PUI. This has the disadvantage that large transient voltage fluctuations occur when switching, and in the case of an intermittent drop in the output of the current unit PUI, DC is supplied from the current unit PUI again after recovery. Spare machine P
It is necessary to set the output voltage of U2 somewhat low, and there is a drawback that it is difficult to satisfy a predetermined voltage fluctuation rate when stably used at a low output voltage.

An object of the present invention is that even if the output voltages of two parallel-connected DC stabilized power supplies are set to the same value, DC is mainly supplied to the load from the DC stabilized power supply selected for the active machine, and the standby machine The above-mentioned drawbacks are eliminated by allowing a current of a certain value determined by the ratio of the dividing resistors to flow from the DC stabilized power supply selected in advance, and a very stable and highly accurate DC voltage can be used in the current situation. An object of the present invention is to provide a control circuit for switching between active and standby power sources, which enables output from a machine or a standby machine.

Describing the configuration of the present invention, the present invention provides a working and standby power supply circuit in which the outputs of two DC stabilized power supply circuits PUI and PU2 are connected in parallel to a load.
Set the output voltages of 2 to almost the same value, and
The output of PU2 is connected to the load through resistor R2 and diode D1, and the output of PU2 is connected to resistor R12 and diode Di.
The diode D is connected to the load via it, and the diode D
The load side voltage of 1 is given as an output voltage detection signal, so that the active unit PUI supplies DC to the load, while for the standby unit PU2, the resistor R12 is divided into resistors with respect to the common return line on the power supply side. By applying the potential as an output voltage detection signal and appropriately selecting all of the resistance division potentials, the current value Ill flowing through the series circuit of resistor R12 and diode Dll on the standby unit PUZ side can be set to The current flowing through the series circuit of diode Dl is set to an arbitrary value that is much smaller than the current flowing through the series circuit of diode Dl.Next, if the working machine PUI is unable to supply DC for some reason, the current working machine PUI's output It is detected that the voltage on the power supply side of the series circuit of the resistor and diode connected to This is a current/standby power supply switching control circuit that switches to the voltage on the load side of a series circuit of a diode and a diode.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail by way of embodiments with reference to the drawings.

FIG. 2 shows a circuit diagram of an embodiment of the invention. In FIG. 2, the current/standby power supply switching control circuit of this embodiment includes an unregulated DC power supply 1, a main control circuit 2, an error amplification circuit 3, a reference voltage generation circuit 4, and a power supply output terminal 6. , a known DC power supply circuit PUI consisting of a detection signal input terminal 7, a common retrace terminal 8, and an overvoltage detection seat circuit 5, an unregulated DC power supply 11, a main control circuit 12, and an error amplification circuit 1.
3, reference voltage generation circuit 14, and detection signal input terminal 17
, common return terminal 18 , and overvoltage detection seat circuit 15
A known DC stabilized power supply circuit PU12 consisting of a series circuit of a resistor R2 and a diode D1, a series circuit of a resistor R12 and a diode Dll connected to the power supply (support) blade terminals 6 and 16, respectively, and a diode D1. and a load 9 connected between the cathode of Dll and the common return terminals 8 and 18, and a P whose emitter is connected to the power supply output terminal 6.
NP) transistor Q1, PNP) resistor R3 connected between the collector of transistor Q1 and detection signal input terminal 7, and resistor R4 connected between detection signal input terminal 7 and the cathode of diode D1. , a resistor R5 connected between the detection signal input terminal 7 and the common retrace terminal 8, a comparator z1 whose non-inverting side input terminal is connected to the cathode of the diode D1, and the output of the comparator z1 and the transistor Q1. A resistor R connected between the base of
1, a resistor R6 connected between the inverting input terminal of the comparator z1 and the power output terminal 16, and a PNP transistor Ql whose emitter is connected to the power output terminal 16.
a resistor R13 connected between the collector of the PNP transistor Qll and the detection signal input terminal 17; a resistor R15 connected between the detection signal input terminal 17 and the common return terminal 18; The non-inverting side input terminal is connected to the cathode of diode Dll! 1ltl comparator Zll,l
! :, output of comparator ZII and transistor Ql
A resistor R11 is connected between the 10 bases, a resistor R16 is connected between the inverting side input terminal of the comparator Zll, and the power supply output terminal, and one contact is connected to the inverting side input terminal of the comparator z1, and the resistor R16 is connected between the inverting side input terminal of the comparator Zll and the It is composed of a toggle switch SWI whose inverting side input terminal Kb contacts are respectively connected and whose common contact C is connected to a common retrace terminal 8, and a capacitor C1 connected in parallel to a load 9.

! To explain the operation of the circuit shown in FIG. 2, the voltages after passing through the diodes of the known DC stabilized power supply circuits PUI and PO2 are set in advance to approximately the same voltage v3,
Assuming that the contacts & and C of the toggle switch SWI are made, the potential of the inverting side input terminal of the comparator z1 is always low (PNP), the transistor Q1 is turned off, and the DC stabilizing power supply circuit PUI passes through the diode D1. It operates so that the subsequent voltage becomes v3, thus supplying direct current to the load 9, and becomes an active machine. In this state, since the anode potential of the diode D1 is higher than the cathode potential, the inverting input terminal of the comparator Zll has a higher potential than the non-inverting input terminal, so the transistor Qll is turned on, and at this time, the DC stabilized power supply circuit PU2 is turned on. Resistor R
13, R15, and 114 becomes approximately v3, so no current flows through the resistor R14, and the potential of the power output terminal 16 tvc2. Diode Dl
l+7)1m! If the pressure drop is 1VD11, VC2,V
An idling current Ill determined by the values of DII and resistors R2, R3, and R5 as shown in equation (1) flows to the load through the diode Dll.

VC2/ (R3+R5)=V3/R51111IR1
2+VD11+V3=VC2 From the above formula, Ill = (R3V3 / R5-VDI 1)
/R12・---・11) Next, if the current machine PUI is unable to supply DC to the load 9 due to some kind of failure, or if the overvoltage shield circuit 5 is activated, the diode D1 Although the potential on the anode side drops rapidly, the potential on the cathode of the diode D1 drops only gradually due to the accumulated charge of the capacitor π1.

Therefore, the inverting side input potential of comparator Zll becomes lower than the non-inverting side input potential, the output of Zll becomes high level, transistor QIIH is turned off, and resistor R14
If the value of is sufficiently smaller than the value of the resistor R15, the DC stabilized power supply circuit PU2 starts operating so that the cathode potential of the diode Dll becomes v3, and for the load 9, the voltage is determined by the above formula +11. Starting from an initial state of nine idle link currents Ill, a direct current is supplied.

In this way, capacitor CI, resistors R1 to R6,
By selecting appropriate values for R11 to R16, switching from the active machine to the standby machine is performed with an appropriate idle link current flowing through the standby machine, and transient voltage fluctuations at load 9 at the time of switching are minimized. It is possible to make it smaller and is still in use,
The steady voltage applied to the main load 9 in both the standby units can be set to approximately the same v3, and the voltage stability is improved accordingly.

As explained above, by configuring the circuit of the present invention, there is an effect that transient voltage fluctuations and steady voltage fluctuations with respect to the load during active and standby switching can be made extremely small.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional example, and FIG. 2 is a circuit diagram of an embodiment of the present invention. The symbols used in the drawings indicate the following. PUI, PO2-・・・DC stabilized power supply circuit, 1,
11...--Unregulated power supply circuit, 2.12...
...Main control circuit, 3゜13...Error amplification circuit,
4, 14...Reference voltage generation circuit, 5, 15...
...Overvoltage detection shield circuit, 6, 16...
-Power output terminal, 7.17...Detection signal input terminal, 8.18...Common return terminal, 9...-
・Load, R1-R6...Resistor, Z 1. Zl
1...Comparator, Ql, Qll...
...Transistor, DI, Dll...Diode, C1...Capacitor, SWI...
toggle switch. Agent Patent Attorney Kuri 1) Haru Yu 1-Yu, Prisoner

Claims (1)

[Claims] In the active and standby power supply circuits in which the outputs of two DC stabilized power supply circuits PUI and PU2 are connected in parallel to the load, the P
Set the output voltages of UI and PU2 to be approximately the same value, connect the output of PUI to the load via resistor R2 and diode DIQ, and connect the output of PU2 to the load via resistor R12 and diode D 11 . jiL load, and the voltage on the load side of the diode 'D1 is applied as an output voltage detection signal to one of the two power supply circuits, for example, the current machine, PUI, so that the current machine PUI is connected to the load. DC is supplied to the standby unit PU2, while the resistor R
By applying the resistor divided potential for the common return line on the power supply side of 12 as an output voltage detection signal and selecting the resistor divided potential appropriately, the value of the current flowing through the series circuit of the standby unit PU2's resistor R12 and diode Dll can be determined. 11tt, set it to an arbitrary value much smaller than the current II flowing through the series circuit of resistor R2 and diode D1 of the current machine PUIII, and then set it to an arbitrary value that is much smaller than the current II flowing through the series circuit of resistor R2 and diode D1 of the current machine PUIII. In this case, it is detected that the voltage on the power supply side of the series circuit of the resistor and diode connected to the output of the active unit PUI becomes lower than the load side voltage, and the output voltage detection signal of the standby unit PU2 is immediately transmitted. , a working/standby power supply switching control circuit, which is connected to the output of the standby unit PU2 and is switched to a voltage on the load side of a series circuit of a photoresistor and a diode.